Recently, due to urgent needs for energy conservation, there has been an increasing need for insulation of greater thickness which generally provides a greater insulating value or an R value, e.g., R values on the order of R-38 or more. It has been a common practice to laminate or glue together two relatively thin insulation batts in order to form a relatively thick insulating batt. However, lamination of insulating batts is somewhat cumbersome because of problems associated with ensuring a complete alignment of the exterior edges of the individual batts forming the final relatively thick insulation batt.
More recently, a manufacturer of insulating material has taken an insulating blanket and has partially cut through the insulating material in order to form a continuous fibrous hinge between the formed insulating batts. Proximate the terminal portion of the insulation production line, a worker uses the hinge to help in aligning the two insulating batts to be joined. Unfortunately, because of the nature of fibrous insulations, this continuous hinge is unsatisfactorily unwieldly and does not allow for a substantially perfect alignment of the exterior edges of the insulation batts. Furthermore, the final laminated batt or product has an objectionable bulge on the side of the laminated batt where the original continuous fibrous hinge was formed.
In another process of the manufacture of fibrous insulation, an insulation blanket is slitted along the machine direction into a plurality of insulation batts separated by a plurality of fibrous pillars. Notched slitter blades are used to form the discontinuous slits between the batts in order to insure that the batts are aligned as they are conveyed towards the packaging area of the fibrous insulation manufacturing line. If the batts were completely separated, they could become misaligned making packaging difficult. However, the relatively thin batts in this process have never been laminated to form a relatively thick insulation product.